I’m exporting data to a SQL Server using the export module. However my floating point values are changing a lot but I want to filter out these changes to only log changes which are more than a certain dead band.
How can I do this filtering for the data I’m reading using modbus. I do not mind filtering in the modbus driver, the SCADA server or the export module.

If you mean you need export changes when the difference between the current and the previous values is greater than a deadband (curVal – prevVal > deadband), it is better to use a stored procudure because logic is more complex.

What is the reason for filtering? If you try to minimize communicating with SQL Server my approach is not suitable for the case.

Thanks for the suggestions. I’ll look into it. However it would be nice to be able to have a filtering (deadband) for each point in the input channels configuration so each point can have its own deadband value. Next the communication server uses this dead band value so that only significant value changes are being handled by the system.

As soon as I have more time I’ll let you know how I could get the system to work as I need.

Finally it will not be a good solution for me to use a stored procedure to compare with the last value and only log when the change is more than a certain value. This is because we want to log a more than 1500 tags (I do not know the exact amount yet) and I would need to have different values for the deadband for different tags. We will use the minute archive data instead.

I still think that a deadband in the communication server would be a nice feature to reduce the amount of realtime data.